Various methods are known in the art for optical 3D mapping, i.e., generating a 3D profile of the surface of an object by processing an optical image of the object. This sort of 3D profile is also referred to as a 3D map, depth map or depth image, and 3D mapping is also referred to as depth mapping.
Some methods of 3D mapping use time-of-flight sensing. For example, U.S. Patent Application Publication 2013/0207970, whose disclosure is incorporated herein by reference, describes a scanning depth engine, which includes a transmitter, which emits a beam comprising pulses of light, and a scanner, which is configured to scan the beam, within a predefined scan range, over a scene. The scanner may comprise a micromirror produced using microelectromechanical system (MEMS) technology. A receiver receives the light reflected from the scene and generates an output indicative of the time of flight of the pulses to and from points in the scene. A processor is coupled to control the scanner and to process the output of the receiver so as to generate a 3D map of the scene.
U.S. Patent Application Publication 2016/0146939, whose disclosure is incorporated herein by reference, describes a scanning device based on a scanner, which includes a base and a gimbal, mounted within the base so as to rotate relative to the base about a first axis of rotation. A transmit mirror and at least one receive mirror are mounted within the gimbal so as to rotate in mutual synchronization about respective second axes, which are parallel to one another and perpendicular to the first axis. A transmitter emits a beam including pulses of light toward the transmit mirror, which reflects the beam so that the scanner scans the beam over a scene. A receiver receives, by reflection from the at least one receive mirror, the light reflected from the scene and generates an output indicative of the time of flight of the pulses to and from points in the scene.